1. Field of the Invention
The present invention relates to an ink jet printing head used in an ink jet printing apparatus which performs printing operations by ejecting liquid such as ink.
2. Description of the Related Art
There is a demand for an ink jet printing head mounted on the ink jet printing apparatus (hereinafter, also referred to as a “printer”) to reduce costs of constituent parts thereof to facilitate manufacturing and assembling thereof, in order to inexpensively provide users with the printing head. Further, there is a demand for the printing head to decrease a number of parts thereof as much as possible also from environmental concerns.
Here, a print element substrate of the ink jet printing head, and an electric wiring member which is generally flexible so as to dispose on a casing of the ink jet printing head (or a casing of an ink jet cartridge) along a side surface thereof, are joined to each other by, for example, bonding or the like. In addition, as disclosed in Japanese Patent Application Laid-open No. 8-300687 (1996), the print element substrate and a back surface of the electric wiring member are fixed to the casing by adhesion or the like after having been aligned to a predetermined position of the casing. Here, also with respect to an area of the electric wiring member where electrical signal input terminals are disposed, the area is fixed to the casing by adhesion or the like after being bent along the side surface of the casing. On the other hand, the casing and a passage member are previously joined to each other by ultrasonic welding or the like. Thereafter, the absorbers are inserted, ink is injected into the absorbers, and the cover member is joined to the main body member, whereby an ink jet cartridge is completed.
The configuration as described above has an advantage that manufacturing costs are low because the number of parts is small, and because the printing head can be assembled in simple processes.
In the configuration of the printing head as described above, while the area of the electrical signal input terminal portion in the electric wiring member is fixed to the main body member by using the adhesive agent or the like, there are constraints on usable adhesive agents. More specifically, the adhesive agent needs to be selected in consideration of, for example, whether the adhesive agent matches well with ink, whether gas and the like are generated in a process where the adhesive agent cures, whether characteristics of the adhesive agent, curing conditions, and the like are suitable for achieving a target production tact, and the like. Additionally, there is such a problem as that, because an adhesion process is incorporated in manufacturing processes, the adhesion process necessitates a cost increase. For this reason, and also in view of cost reduction, it is preferable that use of the adhesive agent be avoided as much as possible.
For the above purpose, as a configuration using no adhesive agent, consideration can be made for a configuration where several points around the area of the electrical signal input terminal portion are fixed by heat caulking. In this case, however, the casing and the back surface of the electric wiring member cannot be completely attached firmly to each other, and a gap is generated therebetween. Such a gap canal so be generated in a portion where adhesion is insufficient in a case of a conventional printing head using the adhesive agent.
On the other hand, there is a case where, on the side surfaces of the casing, drops of water are generated as a result of generation of dew condensation. Furthermore, there is a case where ink mist, which is generated through repetitive ink ejection from ink ejection openings, is accumulated in each portion of the printing head, and forms drops of ink. Moreover, operations (recovery operations) are sometimes performed on the printing head for maintaining, or for recovering, ink ejection performances in a favorable state. Specifically, the recovery operations include: a process for forcedly discharging ink from the ejection openings by causing a suction force and the like to act upon the ink; and a process for wiping a surface (ejection face), on which the ejection openings are provided, of the print element substrate. There is a case where, when these recovery operations are performed, ink attached to the ejection face, or ink wiped away by the wiping process moves toward the electric wiring member from a portion connected with the print element substrate. Subsequently, due to capillary force, liquid, such as ink and water drops, moves through a gap between a supporting surface of the casing and a supported surface of the electric wiring member. Thus, the liquid may possibly spread out along the area of the casing where the electric wiring member is arranged.
Incidentally, there is a case where the electric wiring member is formed by using a TAB tape in view of cost reduction. In this case, by punching a lengthy matrix of the TAB tape on which a wiring (including copper foil, and a plated part formed of Au, Ni, or the like, for protecting the copper foil) as a conductive member is formed, the TAB tape is processed into the electric wiring member having a desired shape and desired dimensions. Accordingly, the conductive wiring member is exposed through an end section of the TAB tape, the end section being located on a side of the area where the electrical signal input terminals for establishing electrical connection with the outside are disposed.
Accordingly, when liquid comes moving to this end section due to the capillary force, the exposed conductive member and the liquid make contact with each other, whereby there arises a risk of causing an electrical trouble, such as occurrence of an electrical short circuit, or corrosion of the wiring.
As a response to this problem, consideration can be made for adopting a configuration where an exposed portion of the conductive member in the end section of the electric wiring member is sealed with a sealing material. In this case, however, there arise the same problems as in the aforementioned case where the adhesive agent is used, and use of a sealing material is not preferable.